a. Field of the Invention
Broadly speaking, this invention relates to radar. More particularly, in a preferred embodiment, this invention relates to methods and apparatus for preventing interference between radar systems illuminating a common target.
B. Discussion of the Prior Art
From time to time, it becomes necessary to physically locate two or more radar systems in spatial proximity to one another. In a fixed installation, interference between the systems is minimized by assigning each system to a different operating frequency. However, where the radar systems are mobile, for example in a tactical military situation, or where frequency congestion makes the assignment of different operating frequencies impossible, interference between the systems is unavoidable.
Actually, there are two situations where interference of this type may arise. The first is where each antenna can physically "see" the other; this is by far the worst case. The other situation is where the two radars are masked from one another, for example, by some intervening hill or building, but they both illuminate some common target.